30 



TOPOGRAPHICAL ANATOMY OF THE 



The cavities of the heart. 



Airium'^ dextriim. — As an examination of the exterior of the heart 

 has already shown, each atrium is divisible into a main part in- 

 timately connected with the other atrium and the ventricle of its own 

 side, and a freer part or auricle (auricula cordis). 



Like all the cavities of the heai't, the right atrium has a smooth 

 glistening lining, the endocardium; but the wall of the auricle is 



V. azygos. 



Branches of a. pulmonalis 

 Aorta. 



Truncus brachiocephalicus. 



Vena cava cranialis. 



^1 



Vv. 

 Pulmonales. 

 Fossa ovalis.'"' 

 Intervenous tubercle ^• 

 Vena cava caudalis.'"" 

 Coronary sinus. -^ 

 Chordae tendineae 



V. cordis media 



Auricle of right atrium. 

 Tricuspid valve. 



- Conus arteriosus. 



- Papillary muscle. 



Transverse muscle. 



A. coronaria dextra 

 (ramus descendens). 



YiG. 13. The heart and fjreat blood-vessels viewed from the ricrht, with the 



interior of the right atrium and right ventricle exposed. In taking 

 away the wall of tlie ventricle, one ot the cusps of the tricuspid valve 

 was al.<o removed. 



rendered uneven by the presence of reticulated muscular ridges of vary- 

 incr height, the musculi pectinati} The ridges end at a semilunar 

 crest (crista terminalis), which corresponds in position to a shallow and 

 often very imperfectly defined groove,, the sulcus terminalis, on the 

 exterior of the atrium. 



1 Atrium [L.], antechamber, the hall or principal room in a Roman house. 



2 Peden [L.], a comb. From the comb-like arrangement of the muscular ridges. 



